1. Field of the Invention
The field of the invention relates to electronic processing for audio or video signals that are output by an output device, such as audio speakers and/or a video display.
2. Background of the Related Art
Recorded audio or video source material may be played back from a source device (such as a compact disc player, stereo, DVD player, computer, television, laptop, MP3 player, cassette player, radio, etc.) reading data from an audio or video source (such as a compact disc, DVD, CD-ROM, flash memory, random access memory (RAM), tape, cassette, AM/FM or satellite radio signals, etc.), and output to an audio or video output device (such as stereo speakers, earphones, computer monitor/display, analog television screen, LCD screen, plasma screen, etc.).
Typically, the listener (in the case of audio) or viewer (in the case of video) has few options in terms of optimizing or improving the sound or image quality in order to enhance the user's experience. For playing an audio source, for instance, the user may adjust bass and treble settings. This has the effect of boosting bass or treble tones, respectively. For playing back a video source, the user may be able to adjust contrast, brightness, or hue, for example. Bass/treble tone controls and video output controls are often built into the source device (such as the radio or stereo unit) or the output device (such as the LCD screen or computer monitor).
One example of a mechanism for modifying audio source material is an equalization or EQ filter (also known as an equalizer), which may be either integrated with the source device or else provided as a separate stand-alone unit. An equalization filter allows the user to manually adjust certain parameters, typically frequency response characteristics, which determine the overall shape of the filter's transfer function. Such a filter is generally used to improve sound fidelity by, e.g., providing more uniform frequency response, to emphasize certain instruments or boost certain frequencies (such as bass tones), to remove undesired noise (such as hiss), or to create new or different sounds. Equalizers may be designed with various analog or digital filters. Equalizer filters include sub-types such as parametric equalizers, graphic equalizers, and notch filters.
While equalizers provide some control over audio selection, they are complicated and inconvenient for many casual listeners. Also, they may require expensive and complex internal filters, and often require significant space and numerous control inputs (e.g., knobs or levers).
Some audio handheld devices, such as certain types of conventional MP3 players, have more advanced user selectable equalization settings tailored for specific types of music. For example, such a device may have different user-selectable equalization settings that are preset for classical music, pop music, hip-hop music, and so on. While this provides some simplification for the user, the user is still generally limited to the options that are provided by the specific device.
Similar limitations or restrictions as those described above generally exist, at least to some extent, with reproduction of live audio or video source material. That is, there are limited options that are available for modifying or improving live audio or video that is captured by an audio or video capture device and sent to an audio or video output device.
It would be advantageous to provide a means for selectively modifying audio or video data for use with an output device, to improve the perceived sound or visual quality of the audio or video source material. It would further be advantageous to provide a means to tailor an audio or video source to a particular type of audio or video output device.